1. Field of the Invention
The present invention relates to an inorganic layered material, and in particular relates to a method for fabricating an exfoliated inorganic layered material.
2. Description of the Related Art
Of various inorganic layered materials, clay is a common silicate mineral found in nature. With the advantages of small particle sizes, a crystalline layered arrangement, acid and alkali resistance, heat resistance and high mechanical strength, clay is filled into polymer (used as a filler or reinforcement) to form composite materials to enhance thermal and mechanical properties thereof. A key factor for fabricating the composite material is that clay should be well dispersed in the composite material. In the conventional method, clay is firstly modified, and then the layered structures of clay are disrupted by the force of polymerization reaction to obtain exfoliated clay.
In U.S. Pat. Nos. 6,822,019, 6,765,050 and 7,022,299, and TW patent No. 1280261, a polyamine with multi-functional groups and highly branched structures is used as an organic exfoliating agent. Inorganic clay is exfoliated by the organic exfoliating agent to obtain a disordered nano-silicate plate.
In TW Publication Application No. 200924840, charges in clay are exchanged with metal ions. Then, the metal ions are reduced by a reducing agent to obtain disordered nano-silicate plate clay.
In TW Patent No. 1270529 and U.S. Pat. No. 7,125,916, amine-terminating oligomers (AMO) are obtained by polymerization of polyoxypropylene diame, p-cresol and formaldehyde and are used as an intercalating agent. Exfoliated clay is exfoliated by the displacement reaction of AMO. A solution comprising a hydroide or a chloride of alkali metal or alkaline-earth metal, ethanol, water, an organic solvent and exfoliated clay are mixed and filtered to obtain layered nano-silicate plates.
U.S. Pat. No. 6,649,713 discloses clay, first being modified by aliphatic amine and then silica, wherein titanium dioxide nanometer particles are then incorporated into the clay by a sol-gel method. Next, by polymerization of the catalyst (such as ethylene or propylene) and the above mixture, a clay nanocomposite material is obtained.
However, the above-mentioned exfoliating methods are all applied to clay. Thus, there is a need to develop an exfoliating method which is applied to inorganic layered material other than clay.